johnson



L. F. JOHNSON.

Furnace Door.

Patented Oct. 6, 1868.

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LUMAN F. JOHNSON, OF BUFFALO,NEW YORK.

am Patent No. 82,721, dated 0mm 1868.

IMPROVEMENT IN FURNACE-DOORS.

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ALL WHOM IT MAY CONCERN:

Be it.known that I, LUMAN F. JOHNSON, of the city of Bufi'alo, countyof Erie, and State of New York, have invented a certain new and useful Improvement in Furnace-Doors; and I do hereby declare that the fol lowing is a full and exact description thereof, reference beinghad to the accompanying drawings, making a part of this specification, in which- Figure I is an elevation,-

Figure II a vertical section, aiid Figure III a horizontal section.

My invention relates to a door for furnaces, composed of a cast-iron frame lined with fire-brick, and con sists in protecting the flangeor flanges of the cast-iron frame which hold the brick against the destructive-action of the intense heat to which doors of this class are subjected, by forming the brick with a rebate, so that they may overlap said flanges, and prevent the direct action of the heat thereon, and the consequent burning thereof, as will hereinafter more fully appear. I

It is a well-known fact that furnace-doors as commonly constructed, (that is, with a cast-iron frame lined with common fire-brick cemented therein,) are quickly destroyed by the heat, which burns and warps the castiron frame, so that it fails to retain the brick. Frequent delays in the running of the furnaceare the cousequent result.'

In the drawings A represents-the iron frame of the door, provided with dove-tail flanges a a, at the centre and at each edge.

B B show the fire-bricks, which are moulded with corresponding dove-tails b 6 rebated from the edge of the iarick, so that when the brick are inserted in the frame, they may overlap and cover the flanges a a, as clearly shown at (Z, so as to protect said flanges against the heatof' the furnace.

This arrangement prevents the heat from the furnace from striking the cast-iron frame until it shall have first passed through. the thickness of the fire-brick, when its intensity will have diminished to an eirtent to render its efl'ect upon the cast iron harmless.

The external flange a extends entirely around the door, but the part across the upper side of the door is made separate, and secured by bolts (1, so that-it may be taken off for the insertion or removal of the fire-brick.

It has been demonstrated by experience, that a furnace-door made according to my invention will last and keep in good order-many times longer than the ordinary door in which the cast-iron frame is unprotected- What I claim, and desire to secure by Letters Patent, is

The'rebated fire-bricks B, so arranged Within the cast-iron frame, as to overlap the flanges a. thereof, and protect the same, substantially as described. i

I LUMAN F. JOHNSON.

Witnesses B. H. MunnLE, F. A. LANewonTHY. 

